1. Field of the Invention
The present invention relates to a method and system for associating an optical device with a data carrier, more particularly it relates to determining the characteristics of an optical device based on the information carried by the data carrier.
2. Description of the Prior Art
Optical components are items that are used to bend, split, diffuse, reflect or otherwise alter or refocus light wavelengths. These optical components are usually formed from a piece of shaped glass or plastic, among other materials. Optical light sources include astronomical objects, or devices that produce or radiate light when excited, such as, lasers, diodes, and lamps. The light produced can be in the visible range, the infrared range or ultraviolet ranges, of the electromagnetic spectrum.
One class of optical components is found in imaging systems, such as, a monocular, binoculars, telescopes, spotting scopes, telescopic gun sights, theodolites, microscopes, medical equipment, or cameras. Another class is directed towards ophthalmic devices for the correction of visual impairments such as myopia, hyperopia, presbyopia, and astigmatism. Such devices are typically corrective lenses, contact lenses, or eyeglasses.
The contact lens market in the United States is a multi-billion dollar market. Recent data indicates that nearly 36 million Americans, almost 13% of the US population, wear contact lenses. There are numerous manufacturers of contact lenses and many different channels of distribution, including eye care practitioners (e.g., ophthalmologists and optometrists), national and regional optical chains, mass merchants, and mail order and online stores. The contact lenses include any of the following basic types: soft, rigid gas permeable and hard. Soft contact lenses are made of a highly flexible material such as a plastic hydrogel polymer, hydroxyethylmethacrylate (HEMA) that contains water or silicone or hydrophilic hydrogels. Rigid gas permeable contact lenses, frequently referred to as RGP contact lenses, are composed of a firm plastic material and do not contain water. RGP lenses permit oxygen to pass directly through the lens to the eye, thus these lenses are gas permeable. In contrast, hard contact lenses are made of a hard plastic material, such as polymethyl methylacrylate (PMMA), which does not allow oxygen to pass through the lens to the eye.
One issue facing lens wearers, eyecare practitioners, and the industry, has been the inability to readily distinguish between lenses intended for the left eye and/or the right eye. This is particularly relevant in such instances where the lenses are unwittingly mixed-up. Typically, mix-ups can occur at various stages, such as, during their manufacture, shipment or preparation in the office of a fitter, or by the user. To counter this problem, contact lenses are often manufactured with identifying marks, which have been hailed as being helpful in distinguishing between the right and left contact lenses. These marks include alphanumeric characters, such as serial numbers, lot and batch numbers, brand name, and optical powers, and may be located on the edge of the lens. However, these methods depend on the visual inspection of the lenses by the user in order to interpret the markings, which is not strictly useful for a user with already impaired vision, and thus may be undecipherable. The methods for providing identifying marks are well known, and include, using a laser, electrical discharge, machining, mechanical scribing, diamond scribing, ultrasonic scribing, holographic marking, and scattering by surface disruption. Also, these identification methods are manufacturing intensive, and require the use of expensive equipment.
Yet another problem facing users and the industry is the inability to readily determine which surface of the lens should be disposed against the eye. This problem has been further exacerbated by the development of newer polymers for soft contact lenses, in which the thickness of the lenses has been steadily reduced to the point where the lenses can easily end up being inside out, instead of right side out. In this orientation the lens can distort the optical properties of the lens, and may cause discomfort to the eye and in some instances can result in eye damage. Prior art methods to solve this problem, apart from using markings as described above, include recommendations to users to verify that the lens is not turned inside out by placing on their forefinger and checking its profile. In this method, it is stated that the lens should assume a natural, curved, bowl-like shape, however, if the lens edges tend to point outward, then the lens is inside out. Another method is to gently squeeze the lens between the thumb and forefinger, and if the lens is right side out then the edges should turn inward, otherwise the edges will turn slightly outward and the lens is thus inside out. It is clear that these methods are subjective, time-consuming, and may even be frustrating for a user, while still presenting a substantially low chance for correct lens orientation determination.
Further, certain types of defects in the eye can only be corrected by lenses which are not spherical. For instance, to effectively correct for astigmatism or presbyopia, the lens is manufactured so that it exhibits different optical properties at different portions thereof. As such, correction of astigmatism involves accurately aligning the principle power meridians of the lens with the principle refractive meridians in the eye, and maintaining the lens at a specific orientation with respect to the meridians of the eye. Misalignment errors will prevent proper correction of astigmatism. Such lenses include spherically asymmetrical lenses or toric lenses. One method for maintaining the lens in particular orientation involves constructing the lens with its intended bottom third thicker than its intended top two thirds, or the lens includes a relatively thick central zone and thinner top and bottom zones. However, because of irregularities in the shape of the cornea, interference by the lower lid, the lens does not stay in its preferred orientation, and may settle to a position that is rotated 5 or more degrees from its intended position. This rotation must be measured and taken into account in the cylinder portion of the lens prescription. One prior art method for measuring the rotation includes placing a trial lens on the eye of the patient and, with a slit lamp, projecting a narrow beam of light across the center of the patient's pupil and a reference point. The angle formed by the narrow light beam and the vertical is considered to be the rotation of the lens. However, such a method is uncomfortable for the user who is subjected to looking at the light, and decentralization of the pupil with respect to the center of the cornea, or of the lens with respect to the center of the cornea, or both can cause the measurement to be inaccurate.
In most countries, contact lenses are classified as medical devices, and are thus normally only dispensed with a valid prescription from a qualified eyecare practitioner. A valid prescription typically includes user's name, eye practitioner's name, contact lens brand name and material, lens measurements such as power, diameter and base curve, directions for safe use such as wearing schedule, whether lenses are for daily or extended wear, the number of refills, whether lens material substitutions are allowed and an expiration date. Generally, the quality of human vision worsens with age, or due to reasons independent of aging or eye diseases. Some of the changes in eyes are reduction in pupil size and the loss of accommodation or focusing capability, or presbyopia. As such, prescriptions typically have an expiration date, and thus should be updated periodically. Each lens manufacturer has a replacement schedule of a contact lens, that is, how long the lenses can be safely worn before discarding. The replacement schedule depends on the patient, manufacturer or the type of lens chosen.
For example, RGPs last several years, while soft contact lenses come in a wider variety of replacement schedules: daily disposable-1 day, disposable (extended wear)-1 week to 1 month, disposable (daily wear)-2 weeks, frequent replacement (also called “planned replacement”), 1 month to several months, conventional 1-year, depending on brand. Generally, hard contact lenses are available for different wear schedules, such as daily wear, and extended wear or overnight wear. Also, with planned-replacement lenses, an eye care practitioner works out a replacement schedule tailored to each user's needs. For example, for users who produce a higher level of protein in their eyes or do not take as good care of their lenses, it might be healthier to replace the lenses more frequently. Therefore, the onus to keep track of the wearable life of the lenses falls on the user. As such, if a user does not record the date of first use, or subsequent usage, as time passes it can become difficult to recall how long a particular pair of contact lenses has been worn.
Despite recommendations by eye care practitioners to replace lenses as specified in the prescriptions, most users continue to use these lens well past the expiration date or replacement date, whether unwittingly or otherwise. Such practices present a serious safety concern with contact lenses. Extended wear of contact lenses, rigid or soft, beyond the replacement schedule or wear schedule, increases the risk of corneal ulcers, infection-caused eruptions on the cornea that can lead to blindness. Symptoms include vision changes, eye redness, eye discomfort or pain, and excessive tearing. Another sight-threatening concern is the infection Acanthamoeba keratitis, caused by improper lens care. This difficult-to-treat parasitic infection's symptoms are similar to those of corneal ulcers. Several solutions for tracking the wearable life of a contact lens have been presented in the prior art, however these solutions place the onus of tracking the day-to-day wear of the lenses on the user, and are prone to error.
It is thus one of the objects of this invention to mitigate or obviate at least one of the aforementioned disadvantages.